Electrofusion coupling particularly useful for coupling plastic pipes

ABSTRACT

An electrofusion coupling for coupling a first device to a second device, includes a first part having an outer end for coupling to the first device, and an inner end formed with a surface of a curved configuration; and a second part having an end engaging the inner end of the first part and formed with a surface of a complementary curved configuration as the first part. The curved configurations of the two parts is such that the second part may be pivoted to locate its longitudinal axis at different angles with respect to the longitudinal axis of the first part. At least one of the parts is of a thermoplastic material and includes an electrical heater coil embedded along its curved surface for fixing by electrofusion the angular position of the second part with respect to the first part.

RELATED PATENT APPLICATION

This application is a National Phase Application of PCT/IL2004/000137having International Filing Date of 12 Feb. 2004, which claims thebenefit of Israeli Patent Application No. 154578 filed 23 Feb. 2003. Thecontents of the above Application are all incorporated herein byreference

FIELD AND BACKGROUND OF THE INVENTION

The present invention is related to electrofusion couplings for couplinga first device to a second device. The invention is particularly usefulin electrofusion couplings for coupling plastic pipes to other devices,e.g., another plastic pipe, a saddle, a spigot or connector; and theinvention is therefore described below particularly with respect to suchapplications.

Plastic pipes for conducting fluids are commonly joined by electrofusionwherein an electrofusion sleeve is applied over the pipe ends to bejoined and is electrically energized to heat-fuse or weld the plasticsleeve to the pipe ends. When a plurality of pipe sections are thusjoined together by electrofusion to form a continuous line, it iscritical that the longitudinal axes of the pipe sections where joinedtogether be perfectly aligned as any deviation from perfect alignmentwill cause the pipe sections to bend and thereby to produce tensionstresses on one side of the bend and compressional stresses on theopposite side of the bend. Such bending stresses, which can result inearly rupture of the plastic pipe, are frequently difficult to avoidparticularly when joining together short sections of pipe, or whentraversing a curve in the pipeline. In such cases, it is frequentlynecessary to insert specially-dimensioned angular sections or elbows toaccommodate bends without introducing stresses in the joined pipesections. This significantly increases the manufacturing costs, as wellas the inventory and maintenance costs, of the pipe line.

Similar problems may also be involved where a plastic pipe is to bejoined to a saddle, e.g. for receiving another plastic pipe thereacross,or where the plastic pipe is to be joined to a spigot or connector forconnection to another device.

OBJECTS AND BRIEF SUMMARY OF THE PRESENT INVENTION

An object of the present invention is to provide an electrofusioncoupling which can be used for accommodating misalignment between pipesections to be joined by the electrofusion coupling without introducingsuch stresses in the pipe sections or other devices to be joined. Whilethe invention is particularly useful in an electrofusion coupling forjoining a plastic pipe to another plastic pipe, or to another plasticdevice, it can also be used for coupling other types of devices togetherby electrofusion in a manner to accommodate misalignment between the twodevices while maintaining the integrity of the electrofusion system.

According to a broad aspect of the present invention, therefore, thereis provided an electrofusion coupling for coupling a first device to asecond device, comprising: a first part having an outer end for couplingto the first device, and an inner end formed with a surface of a curvedconfiguration; and a second part having an end engaging the inner end ofthe first part and formed with a surface of a complementary curvedconfiguration as the first part, the curved configurations of the twoparts being such that the second part may be pivoted to locate itslongitudinal axis at different angles with respect to the longitudinalaxis of the first part; at least one of the parts being of athermoplastic material and including an electrical heater coil embeddedtherein along its curved surface for fixing by electrofusion the angularposition of the second part with respect to the first part.

According to a more specific aspect of the present invention, there isprovided an electrofusion coupling for coupling a first device to asecond device, comprising: a first part of thermoplastic material havingan outer end for coupling the first device, and an inner end formed witha surface of spherical configuration; and a second part also ofthermoplastic material having an end engaging the inner end of the firstpart and formed with a surface of complementary spherical configurationas the first part, the curved configurations of the two parts being suchthat the second part may be universally pivoted to locate itslongitudinal axis in different planes and at different angles withrespect to the longitudinal axis of the first part; at least one of theparts including an electrical heater coil embedded therein along thespherical surface thereof for fixing the angular position of the secondpart with respect to the first part by electrofusion.

In the preferred embodiments of the invention described below, the outerend of the first part is formed with a bore of cylindricalconfiguration, and the first device is a plastic pipe to be receivedwithin the bore of the first part and to be fixed therein byelectrofusion.

In one preferred embodiment of the invention described below, the end ofthe second part opposite to that receiving the first part is formed withan outer surface of curved configuration, and the coupling furthercomprises a third part including an outer end for coupling to the seconddevice, and an inner end formed with an inner surface of complementarycurved configuration as the outer surface at the opposite end and of thesecond part so as to be rotatable therein to different angular positionswith respect to the second part. In the described preferred embodiment,the third part is also of a thermoplastic material, and the outer end ofthe third part also includes an electrical heater coil embedded thereinfor coupling to the second device also by electrofusion.

In a second described preferred embodiment, the end of the second partopposite to that received within the first part is of a saddle shape forreceiving the second device.

In a described third embodiment, the end of the second part opposite tothat received within the first part is of tubular shape, e.g., to serveas a spigot or as a connector, for coupling to the second device.

In the three preferred embodiments referred to above, the surface ofcurved configuration of the first part is the inner surface at the innerend of the first part, and the surface of complementary curvedconfiguration of the second part is the outer surface at the end of thesecond part which is received within the inner curved surface at theinner end of the first part.

A fourth embodiment of the invention is also described below, whereinthe surface of curved configuration of the first part is the outersurface at the inner end of the first part, and the surface ofcomplementary curved configuration of the second part is the innersurface at the end of the second part which receives the inner curvedsurface at the inner end of the first part.

As will be described more particularly below, an electrofusion couplingconstructed in accordance with the foregoing features allows twodevices, such as plastic pipes, to be coupled together by electrofusionin a manner which accommodates non-alignment and which permits the twodevices to be pivoted to different angles with respect to each other asmay be desired for a specific application.

Further features and advantages of the invention will be apparent fromthe description below.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is herein described, by way of example only, withreference to the accompanying drawings, wherein:

FIG. 1 illustrates a three-part electrofusion coupling constructed inaccordance with the present invention for coupling together two plasticpipes;

FIG. 2 is a longitudinal sectional view of the electrofusion coupling ofFIG. 1;

FIG. 3 illustrates a two-part electrofusion coupling constructed inaccordance with the present invention for coupling a plastic pipe to asaddle;

FIG. 4 is a longitudinal sectional view of the electrofusion coupling ofFIG. 3;

FIG. 5 illustrates a two-part electrofusion coupling constructed inaccordance with the present invention, for coupling a plastic pipe to atubular device, such as a spigot or connector to serve as an outlet tapor the like;

FIG. 6 is a longitudinal sectional view illustrating the electrofusioncoupling of FIG. 5;

FIG. 7 is a longitudinal section view illustrating another two-partelectrofusion coupling constructed in accordance with the presentinvention for coupling a plastic pipe to a saddle;

FIG. 8 is an enlarged sectional view illustrating one of the parts inthe electrofusion coupling of FIG. 7; and

FIG. 9 illustrates a modification in the three part electrofusioncoupling of FIGS. 1 and 2.

It is to be understood that the foregoing drawings, and the descriptionbelow, are provided primarily for purposes of facilitating understandingthe conceptual aspects of the invention and various possible embodimentsthereof, including what is presently considered to be a preferredembodiment. In the interest of clarity and brevity, no attempt is madeto provide more details than necessary to enable one skilled in the art,using routine skill and design, to understand and practice the describedinvention. It is to be further understood that the embodiments describedare for purposes of example only, and that the invention is capable ofbeing embodied in other forms and applications than described herein.

DESCRIPTION OF PREFERRED EMBODIMENTS

FIGS. 1 and 2 illustrate a three-part coupling, generally designated 2,for coupling together two plastic tubes (not shown) such as to permitthe longitudinal axes of the two plastic pipes 2 to be located at anydesired angle with respect to each other in the same plane, or indifferent planes, according to the requirements of the specificapplication.

The illustrated electrofusion coupling 2 includes a first part 10 at oneend for receiving one of the plastic pipes, and a second part 20 at theopposite end for receiving the second plastic pipe. It further includesa third, intermediate part 30 coupling the two parts 10 and 20 togethersuch as to permit each part to be universally pivoted with respect tothe other part to any desired angle within a predetermined range.

Thus, part 10 of electrofusion coupling 2 is formed at its outer endwith a cylindrical bore 11 for receiving its respective plastic pipe(not shown). Part 10 is further formed with an inner annular shoulder 12to serve as an abutment for locating the received plastic pipe. Theopposite end of part 10 is formed with a concavely-curved inner surface13 for receiving the respective end of the intermediate part 30 such asto permit parts 10 and 30 to be pivoted to different angular positionswith respect to each other, as will be described more particularlybelow.

Part 10 further includes an electrical heater coil 14 at the outer endof the part to receive the plastic pipe, and another electrical heatercoil 15 at the opposite end to receive the respective end of theintermediate part 30. The two electrical coils 14 and 15 are connectedin series between two electrical terminals 16 and 17. In someapplications, however, it may be desirable to connect each of the twoelectrical coils 14, 15 to a separate pair of terminals in order toenable them to be energized separately, or together, as desired.

Part 20 at the opposite end of the electrofusion coupling 2 is similarlyformed with: a cylindrical bore 21 for receiving the other plastic pipe(not shown); an annular shoulder 22 serving as an abutment for thereceived plastic pipe; an inner concavely-curved surface 23 at theopposite end of the part for receiving the respective end of theintermediate coupling 30; an electrical heater coil 24 at the end of thepart to receive the plastic pipe; an electrical heater coil 25 at theopposite end of the part to receive the intermediate coupling part 30;and a pair of electrical terminals 26 and 27 for energizing the twoheater coils 24 and 25.

The intermediate part 30 of the electrofusion coupling 2 is formed witha bore therethrough consisting of a cylindrical section 31 at itscenter, and two conical sections at its opposite ends 32, 33. The outersurface of the central section 31 is cylindrical, as shown at 34. Theouter surfaces of the two ends 32, 33, are convexly-curved, as shown at35 and 36, respectively, with a curvature complementary to that of theconcavely-curved inner surfaces 13, 23 of the two end parts 10, 20.

In the preferred embodiment of the invention illustrated in FIGS. 1 and2, the complementary curved surfaces (13 of part 10, and 35 of part 30at one end; and 23 of part 20 and 36 of part 30 at the opposite end) arepreferably of a spherical configuration so as to allow the two end parts10, 20, to be universally pivotable with respect to the intermediatepart 30 to different angular positions in different planes. It iscontemplated, however, that in some applications, it may suffice topivot the two pipes to be coupled to different angular positions withtheir longitudinal axes in the same plane, in which case these curvedsurfaces could be cylindrical, rather than spherical.

The manner of using the electrofusion coupling illustrated in FIGS. 1and 2 will be apparent from the above description. Thus, one of thepipes to be coupled is inserted within bore 11 of part 10 until its endabuts annular shoulder 12; and the other pipe to be coupled is insertedinto bore 21 of part 20 until its end abuts shoulder 22. The two pipesare then pivoted to the desired angle with respect to each other.Electrical coils 14 and 15 are energized via terminals 16 and 17 toelectrofuse part 10 with respect to its received plastic pipe and theintermediate part 30; and electrical coils 24 and 25 are energized viatheir respective terminals 26 and 27 to electrofuse part 20 with respectto the second pipe and intermediate part 30 of the electrofusioncoupling.

FIGS. 3 and 4 illustrate a two-part saddle-type electrofusion couplingfor coupling a plastic pipe to a saddle, e.g., for mounting another pipeat right-angles to it as in a T-fitting. One of its two parts, namely,that for receiving one pipe, is the same as part 10 in FIGS. 1 and 2,and therefore that part and its components are identified by the samereference numerals. The other part is designed to serve as the saddle,and is generally designated 40 in FIGS. 3 and 4.

The second part 40 illustrated in FIGS. 3 and 4 is formed at one endwith a construction similar to the respective end of the intermediatepart 30 in FIG. 2. Thus, part 40 is formed with a bore having a centralcylindrical section 41 and an outer conical section 42 corresponding tobore sections 31 and 32 in FIG. 2. Part 40 is further formed with anouter surface having a central section 44 of cylindrical configurationand an end section 45 of convexly-spherical configuration, correspondingto outer surface 23 in FIG. 2.

The opposite end of part 40 of the electrofusion coupling illustrated inFIGS. 3 and 4 is formed as a curved saddle, as shown at 46, extendingperpendicularly to and communicating with bore section 41 of that part.Saddle section 46 of part 40 includes electrical heater coils 47 and 48at the opposite sides of bore section 41, adapted to be energized via apair of electrical terminals 49, only one of which is seen in FIGS. 3and 4.

The manner of using the electrofusion coupling illustrated in FIGS. 3and 4 will be apparent from the above description. Thus, one pipe isinserted into part 10 of the coupling, as described above with respectto FIGS. 1 and 2, and the other pipe is applied across the curved saddle46 of part 40. Part 40 is then pivoted to the desired angular positionwith respect to part 10. Heater coils 14 and 15 are then electricallyenergized to electrofuse the two parts in the pivoted angular position,and also to electrofuse the plastic pipe within part 10. Electricalheater coil 47 may then be energized to electrofuse the plastic pipewithin the saddle section 46 of part 40.

FIGS. 5 and 6 illustrate a two-part electrofusion coupling in which onepart, that for receiving a plastic pipe, is of the same construction aspart 10 in FIGS. 1, 2 and 3, 4, respectively; that part and itscomponents are therefore identified by the same reference numerals. Thesecond part, identified as 50 in FIGS. 5 and 6, is pivotally mounted atone end to part 10, and is formed at its opposite end into a tubularconfiguration for use, for example, as a spigot, connector, or the like,to serve as an outlet (or inlet) for the fluid conducted within theplastic pipe.

Thus, as shown in FIGS. 5 and 6, part 50 is formed with a boretherethrough having a cylindrical section 51 and a conical section 52 atone end, the latter being formed with an outer surface 55 of convexlyspherical configuration, corresponding to spherical surface 45 in FIG.4, for pivotal movement within the concavely-spherical surface 13 ofpart 10. Thus, part 50 may be pivoted to any desired position withrespect to part 10, and electrofused in that position by electricallyenergizing the electrical heater coils 14 and 15 of part 10, in the samemanner as described above.

FIGS. 7 and 8 illustrate a two-part saddle-type coupling similar to thatof FIGS. 3 and 4, except that in this case the spherical surfaces, whichpermit one part to be pivoted with respect to the other, are reversed inthe two parts. Thus, one of the parts, that indicated 110 in FIGS. 7 and8, is of similar construction as part 10 in FIGS. 3 and 4, except thatthe spherical surface, therein designated 113, is convexly-formed on theouter surface of part 110, rather than concavely-formed on its innersurface; and the spherical surface engaged thereby by the second part140 is concavely-formed on its inner surface, as shown at 145, ratherthan on its outer surface. In all other respects, the two-partelectrofusion coupling illustrated in FIGS. 7 and 8 may be constructedin the same manner as described above with respect to FIGS. 3 and 4 withthe annular shoulder 112 for locating the plastic pipe to be insertedinto part 110, the heater coils 114, 115 for electrofusing the pipe topart 110 and part 110 to part 140, and heater coil 147 for electrofusingthe other pipe to the saddle 146.

It will be appreciated that a similar modification can be made to theelectrofusion couplings illustrated in FIGS. 1, 2 and 4, 5,respectively, namely by providing the spherical surface of part 10 onthe outer surface of that part, rather than on the inner surface, and byproviding the spherical surface of the second part on the inner surfaceof that part rather than on the outer surface.

FIG. 9 illustrates a modification in the three-part coupling of FIGS. 1and 2, particularly in the construction of the third, intermediate part,designated 30 in FIGS. 1 and 2, and 130 in FIG. 9. Since the first andsecond parts 10 and 20, respectively, are of the same construction as inFIGS. 1 and 2, these parts and their respective elements are identifiedin FIG. 9 by the same reference numerals as in FIGS. 1 and 2.

The main modification in the FIG. 9 construction is that, whereas inFIGS. 1 and 2 the inner and outer ends 32, 33 of the third, intermediatepart 30 have a common longitudinal axis, the outer ends 132, 133 of part130 in FIG. 9 have longitudinal axes LAa, LAb, respectively, at an angleto each other. Accordingly, part 130 will also have two centralcylindrical sections 131 a, 131 b and two outer cylindrical surfaces 134a, 134 b, both at the same angle with respect to each other. By thusproviding a fixed angular bend in the third, intermediate part 130, theelectrofusion coupling of FIG. 9 is capable of accommodating largerangular displacements between the two pipes to be coupled together.

While the invention has been described with respect to several preferredembodiments, it will be appreciated that many other variations andapplications may be made. For example, while the two electrical coils(e.g., 14, 15 shown in FIG. 2) are connected in series to a common pairof terminals (e.g. 16, 17), they may be connected in parallel, or to aseparate pair of terminals. In addition, the two or three parts could befixed to each other at the desired angular position by electrofusion,while one or both of the coupled devices (e.g., plastic pipes, saddles,etc.) could be fixed to the respective end of the coupling by mechanicalmeans, such as a compressional, split-ring type mechanical couplings,according to the particular application. Many other variations,modifications and applications of the invention will be apparent.

1. An electrofusion coupling for coupling a first device to a seconddevice, comprising: a first part having a first end for coupling to saidfirst device, and a second end formed with a surface of a curvedconfiguration; and a second part having an end engaging said second endof the first part and formed with a surface of a complementary curvedconfiguration as said first part, the curved configurations of the twoparts being such that said second part may be pivoted to locate itslongitudinal axis at different angles with respect to the longitudinalaxis of said first part; at least one of said parts being of athermoplastic material and including an electrical heater coil embeddedtherein along its curved surface for fixing by electrofusion the angularposition of said second part with respect to said first part.
 2. Theelectrofusion coupling according to claim 1, wherein said curvedconfigurations of said second end of the first part and said end of thesecond part are spherical configurations so as to allow said second partto be universally pivoted to locate its longitudinal axis in differentplanes and at different angles with respect to the longitudinal axis ofthe first part.
 3. The electrofusion coupling according to claim 1,wherein at least said first part is of a thermoplastic material, andsaid first end of the first part also includes an electrical heater coilembedded therein for coupling to said first device also byelectrofusion.
 4. The electrofusion coupling according to claim 3,wherein said first end of said first part is formed with a bore ofcylindrical configuration, and said first device is a plastic pipe to bereceived within said bore of said first part and to be fixed therein byelectrofusion.
 5. The electrofusion coupling according to claim 1,wherein said surface of curved configuration of said first part is theinner surface at the second end of the first part, and said surface ofcomplementary curved configuration of said second part is the outersurface at the end of the second part which is received within saidinner curved surface at the second end of the first part.
 6. Theelectrofusion coupling according to claim 1, wherein said surface ofcurved configuration of said first part is the outer surface at thesecond end of the first part, and said surface of complementary curvedconfiguration of said second part is the inner surface at the end of thesecond part which receives said inner curved surface at the second endof the first part.
 7. The electrofusion coupling according to claim 1,wherein the end of said second part opposite to that receiving saidfirst part is formed with an outer surface of curved configuration; andwherein said coupling further comprises a third part including a firstend for coupling to said second device, and a second end formed with aninner surface of complementary curved configuration as the outer surfaceat said opposite end and of said second part so as to be pivotabletherein to different angular positions with respect to said second part.8. The electrofusion coupling according to claim 7, wherein said curvedconfigurations of said opposite end of the second part and said secondend of the third part are spherical configurations so as to allow saidthird part to be universally pivotable to different angular positionswith respect to said second part.
 9. The electrofusion couplingaccording to claim 7, wherein said third part is also of a thermoplasticmaterial, and said first end of said third part also includes anelectrical heater coil embedded therein for coupling to said seconddevice also by electrofusion.
 10. The electrofusion coupling accordingto claim 7, wherein said second and first ends of said third part have acommon longitudinal axis.
 11. The electrofusion coupling according toclaim 7, wherein said second and first ends of said third part havelongitudinal axes at an angle to each other.
 12. The electrofusioncoupling according to claim 1, wherein said end of the second partopposite to that received within said first part is of a saddle shapefor receiving said second device.
 13. The electrofusion couplingaccording to claim 12, wherein at least said first part is of athermoplastic material, and said first end of the first part alsoincludes an electrical heater coil embedded therein for coupling to saidfirst device also by electrofusion.
 14. The electrofusion couplingaccording to claim 12, wherein said second part is also made of athermoplastic material, and said opposite end of the second part alsoincludes an electrical coil embedded therein for also fixing said seconddevice thereto by electrofusion.
 15. The electrofusion couplingaccording to claim 1, wherein said end of the second part opposite tothat received within said first part is of tubular shape for coupling tosaid second device.
 16. An electrofusion coupling for coupling a firstdevice to a second device, comprising: a first part of thermoplasticmaterial having a first end for coupling to said first device, and asecond end formed with a surface of spherical configuration; and asecond part also of thermoplastic material having an end engaging saidsecond end of the first part and formed with a surface of complementaryspherical configuration as said first part, the curved configurations ofthe two parts being such that said second part may be universallypivoted to locate its longitudinal axis in different planes and atdifferent angles with respect to the longitudinal axis of said firstpart; at least one of said parts including an electrical heater coilembedded therein along its spherical surface for fixing the angularposition of said second part with respect to said first part byelectrofusion.
 17. The electrofusion coupling according to claim 16,wherein said first end of said first part is formed with a bore ofcylindrical configuration, and said first device is a plastic pipe to bereceived within said bore of said first part and to be fixed therein byelectrofusion.
 18. The electrofusion coupling according to claim 17,wherein the end of said second part opposite to that receiving saidfirst part is formed with an outer surface of curved configuration; andwherein said coupling further comprises a third part including a firstend for coupling to said second device, and a second end formed with aninner surface of complementary curved configuration as the outer surfaceat said opposite end and of said second part so as to be pivotabletherein to different angular positions with respect to said second part.19. The electrofusion coupling according to claim 18, wherein said thirdpart is also of a thermoplastic material, and said first end of saidthird part also includes an electrical heater coil embedded therein forcoupling to said second device also by electrofusion.
 20. Theelectrofusion coupling according to claim 16, wherein said end of thesecond part opposite to that received within said first part is of asaddle shape for receiving said second device.
 21. The electrofusioncoupling according to claim 20, wherein said second part is also made ofa thermoplastic material, and said opposite end of the second part alsoincludes an electrical coil embedded therein for also fixing said seconddevice thereto by electrofusion.
 22. The electrofusion couplingaccording to claim 16, wherein said end of the second part opposite tothat received within said first part is of tubular shape for coupling tosaid second device.